Adobe 13101332 - Photoshop - Mac User Manual page 151

Adobe Photoshop Help
Using Help | Contents
To use the Auto Levels command:
Choose Image > Adjustments > Auto Levels.
To change the amount of white and black values clipped:
Do one of the following:
(Photoshop) Set clipping values in the Auto Correction Options dialog box. For more
•
information, see "Setting auto correction options (Photoshop)" on page
(ImageReady) Hold down Alt (Windows) or Option (Mac OS), and click Options in the
•
Levels dialog box. Enter the percentage of extreme highlight and shadow pixels to
ignore, and click OK. A value between 0.5% and 1% is recommended.
Using the Auto Contrast command
The Auto Contrast command adjusts the overall contrast and mixture of colors in an RGB
image automatically. Because it does not adjust channels individually, Auto Contrast does
not introduce or remove color casts. It maps the lightest and darkest pixels in the image to
white and black, which makes highlights appear lighter and shadows appear darker.
When identifying the lightest and darkest pixels in an image, Auto Contrast clips the white
and black pixels by 0.5%—that is, it ignores the first 0.5% of either extreme. This ensures
that white and black values are based on representative rather than extreme pixel values.
Auto Contrast can improve the appearance of many photographic or continuous-tone
images. It does not improve flat-color images.
To use the Auto Contrast command:
Choose Image > Adjustments > Auto Contrast.
To change the amount of white and black values clipped:
Do one of the following:
(Photoshop) Set clipping values in the Auto Correction Options dialog box. For more
•
information, see "Setting auto correction options (Photoshop)" on page
(ImageReady) Hold down Alt (Windows) or Option (Mac OS), and click Options in the
•
Levels dialog box. Enter the percentage of extreme highlight and shadow pixels to
ignore, and click OK. A value between 0.5% and 1% is recommended.
Using the Auto Color command (Photoshop)
The Auto Color command adjusts the contrast and color of an image by searching the
actual image rather than the channels' histograms for shadows, midtones, and highlights.
It neutralizes the midtones and clips the white and black pixels based on the values set in
the Auto Correction Options dialog box. (See
(Photoshop)" on page
To use the Auto Color command:
Choose Image > Adjustments > Auto Color.
Using Help | Contents
| Index
144.)
| Index
Making Color and Tonal Adjustments
"Setting auto correction options
Back 151
144.
144.
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